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When are transfusions of platelet concentrates given?

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Transfusions of platelet concentrates are usually given to prevent haemorrhage in patients who present with low levels of platelets in their blood or where there is something wrong with their platelets. The purpose is to prevent haemorrhage, but platelet concentrates can also be administered to prevent haemorrhage, for example, prior to surgery or after a cancer patient has had chemotherapy.

Given an indication of platelet concentrates, it is very important to evaluate three things:

• the patient’s platelet count and other blood-cell counts and coagulation tests
• the presence of, or risk of, haemorrhage
• the cause of the low platelet count (thrombocytopenia)

A reduction in the platelet count is not, in itself, a reason to carry out a transfusion of platelet concentrates.

Thrombocytopenias: for platelet counts above 50,000 /µ ?l, a transfusion is rarely required except in special circumstances

• What should the dosage be?

In order for the post-transfusion platelet count to increase by about 20,000 / ?l, the appropriate dose for an adult is 3x1011 platelets, in other words, 300 billion platelets.
The quantity of platelet concentrates to be given in a transfusion depends on their origin, i.e. whether they come from:

• aphaeresis:or an adult, the usual dosage is one unit
• leuko-platelet layers: the usual dosage is one platelet concentrate made up from four or five donations of total blood

In paediatrics: 10 ml of platelet concentrate is administered for every kilo the child weighs.

Frequency of treatment will depend on clinical indications. For prophylactic treatments, one dose every 24-48 hours is normal. In the case of surgical interventions, the transfusion is carried out immediately prior to surgery.

• What are the possible side effects?

A platelet transfusion can cause the following side effects (which are more common than with other transfusions):

• febrile reactions: although these are less common due to the use of blood components which do not contain white blood cells (leukoreduced)
• bacterial contamination: although not common, bacterial contamination occurs more often than with other transfusions, as they are kept at a temperature of 22ºC
• alloimmunisation: production of antibodies against different blood components, which could affect the effectiveness of subsequent transfusions

When are transfusions of platelet concentrates given?